Evaporative coolers can be made to cool a localized area by emitting a mist into the area. Personal misting devices serve as evaporative coolers, spraying the mist onto a user's skin and in his vicinity; the evaporation of the mist provides the cooling effect. An easily transportable, handheld misting device, or “mister,” must be pressurized in order to force a contained liquid, usually water, through the atomizer of the device and emit the liquid as a mist. Personal, portable misters can be powered, such as by a battery, to pressurize and/or pump the liquid; however, the container can instead be manually pressurized via a hand pump, eliminating the requirement for a separate power source of pressurization. A typical hand pump is directly attached to a small water tank, and the user manually reciprocates the pump handle to force air into the tank to pressurize it. The device is turned on by opening a flow valve, and a fine mist is emitted from a nozzle.
A common problem for most prior art devices is that the user cannot tell if the container is sufficiently pressurized to emit a fine mist without testing it by opening the valve. A container that is insufficiently pressurized releases large drops of water slowly, rather than spraying a fine mist. Insufficient pressure therefore renders the apparatus useless for its purpose because the emission isn't a mist and, moreover, it is also messy. It would be desirable for the mister to indicate that a sufficient level of pressure has been reached before it is turned on, avoiding drips.
Another problem with prior art devices is that once the tank is pressurized, the handle may not properly seat in a closed position, being pushed out of position by the pressure in the tank.